If murder is an unpardonable sin, why does the Church not speak out against the death penalty? Why are they so okay with it? The leaders have said that it’s something they would rather leave up to the state/country, but that doesn’t make any sense as they have publicly spoken out against other laws/possible laws in the past. Why would they just sit back and be neutral when it comes to murder?
You appear to be conflating the death penalty and murder. The two are not the same. Let’s look at a few scriptures:
Thou shalt not kill. Exodus 20:13
Strong’s definition of the Hebrew word that was translated into English as “kill”:
râtsach, raw-tsakh’; a primitive root; properly, to dash in pieces, i.e. kill (a human being), especially to murder:—put to death, kill, (man-) slay(-er), murder(-er).
As you can see, this command is to not commit murder. Several Old Testament verses clarify the difference between manslaughter (accidentally killing another) and murder (intentionally killing another with malice). Deuteronomy 19 is one of the clearest. After commanding that “Cities of Refuge” be established, the Lord explains that they are places where a person guilty of manslaughter may flee, so that they may live (not receive the death penalty):
4 And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbour ignorantly, whom he hated not in time past;
5 As when a man goeth into the wood with his neighbour to hew wood, and his hand fetcheth a stroke with the axe to cut down the tree, and the head slippeth from the helve, and lighteth upon his neighbour, that he die; he shall flee unto one of those cities, and live:
…Then the nature of and penalty for murder are explained:
11 But if any man hate his neighbour, and lie in wait for him, and rise up against him, and smite him mortally that he die, and fleeth into one of these cities:
12 Then the elders of his city shall send and fetch him thence, and deliver him into the hand of the avenger of blood, that he may die.
13 Thine eye shall not pity him, but thou shalt put away the guilt of innocent blood from Israel, that it may go well with thee.
As you can see, the Lord takes murder, and its required punishment, very seriously.
At this point, you may be thinking this is just an Old Testament thing, but here we see that the same law was had among the Nephites:
Wo unto the murderer who deliberately killeth, for he shall die. 2 Nephi 9:35
And you might be tempted to believe that the Lord, when he did away with the Law of Moses and established the higher law did away with the capital punishment, but here we see the Lord establishing it in this dispensation as well:
And again, I say, thou shalt not kill; but he that killeth shall die. D&C 42:19
Clearly, the Lord has established that there are times when capital punishment is appropriate.